#include <stdio.h> #include <algorithm> #include <iostream> #include <string> #include <vector> #include <functional> #include <map> #include <iomanip> #include <math.h> #include <stack> #include <queue> #include <bitset> #include <cstdlib> #include <tuple> #include <cctype> #include <ctype.h> #include <set> #include <sstream> using namespace std; int main() { int i, j, k; string s; cin >> s; int cnta = 0; for (i = 0; i < s.length(); i++) { if (s[i] == 'B') { for (j = i; j < s.length(); j++) { if (s[j] == 'A') cnta++; } } } cout << cnta << endl; getchar(); getchar(); return 0; }